Condensed Parent Company Only Statements (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Assets        
Cash and cash equivalents $ 429,169 $ 71,469    
Securities available for sale (at fair value) 213,418 205,017    
Total assets 1,947,039 1,661,076 1,712,851  
Liabilities [Abstract]        
Other liabilities 30,147 37,369    
Shareholders' equity [Abstract]        
Preferred Stock (par value $.01 per share) Authorized - 20,000,000 shares, no shares issued 0 0    
Common stock (par value $.01 per share) Authorized - 200,000,000 shares in 2012 and 2011 Issued - 34,072,909 in 2012 and 33,974,450 in 2011 Outstanding - 31,348,556 in 2012 and 31,250,097 in 2011 341 341    
Additional paid-in-capital 110,480 110,490    
Retained earnings 151,195 136,487    
Unearned ESOP shares (854) (1,708)    
Treasury stock (2,724,353 shares), at cost (45,261) (45,261)    
Accumulated other comprehensive income (net of taxes) (1,429) 2,285    
Total shareholders' equity 214,472 202,634 166,372 172,220
Total liabilities and shareholders' equity 1,947,039 1,661,076    
Preferred stock - par value (in dollars per share) $ 0.01 $ 0.01    
Preferred stock - shares authorized (in shares) 20,000,000 20,000,000    
Preferred stock - shares issued (in shares) 0 0    
Common stock - par value (in dollars per share) $ 0.01 $ 0.01    
Common stock - shares authorized (in shares) 200,000,000 200,000,000    
Common stock - shares issued (in shares) 34,073,670 34,072,909    
Common stock - shares outstanding (in shares) 31,349,317 31,348,556    
Treasury shares (in shares) 2,724,353 2,724,353    
Statements of Operations [Abstract]        
Interest income 62,864 69,846 79,352  
Total income (loss) 39,206 41,945 46,516  
Compensation 68,807 63,507 39,159  
Professional fees 2,386 2,109 1,648  
Other expense 10,871 11,971 7,394  
Total expense 99,144 102,138 74,579  
Income (loss) before income tax 23,329 22,710 (6,911)  
Income tax benefit 8,621 (12,204) 562  
Net income (loss) 14,708 34,914 (7,473)  
Cash flows from operating activities [Abstract]        
Net income (loss) 14,708 34,914 (7,473)  
Adjustments to reconcile net loss to net cash provided by operating activities [Abstract]        
Amortization of unearned ESOP shares 718 306 202  
Stock based compensation 126 145 1,593  
Deferred income taxes 5,394 (16,895) (735)  
Change in other assets and liabilities (1,173) (3,352) 2,464  
Net cash (used in) provided by operating activities 52,284 (8,137) 35,090  
Cash flows from investing activities [Abstract]        
Net cash used in investing activities 24,069 91,525 61,454  
Net cash provided by (used in) financing activities 281,347 (92,299) (91,495)  
Net increase (decrease) in cash 357,700 (8,911) 5,049  
Cash and cash equivalents at beginning of year 71,469 80,380 75,331  
Cash and cash equivalents at end of year 429,169 71,469 80,380  
Parent Company [Member]
        
Assets        
Cash and cash equivalents 349 337    
Securities available for sale (at fair value) 5,160 5,070    
Investment in subsidiaries 205,776 195,451    
Other assets 3,276 1,926    
Total assets 214,561 202,784    
Liabilities [Abstract]        
Other liabilities 89 150    
Shareholders' equity [Abstract]        
Preferred Stock (par value $.01 per share) Authorized - 20,000,000 shares, no shares issued 0 0    
Common stock (par value $.01 per share) Authorized - 200,000,000 shares in 2012 and 2011 Issued - 34,072,909 in 2012 and 33,974,450 in 2011 Outstanding - 31,348,556 in 2012 and 31,250,097 in 2011 341 341    
Additional paid-in-capital 110,480 110,490    
Retained earnings 151,195 136,487    
Unearned ESOP shares (854) (1,708)    
Treasury stock (2,724,353 shares), at cost (45,261) (45,261)    
Accumulated other comprehensive income (net of taxes) (1,429) 2,285    
Total shareholders' equity 214,472 202,634    
Total liabilities and shareholders' equity 214,561 202,784    
Preferred stock - par value (in dollars per share) $ 0.01 $ 0.01    
Preferred stock - shares authorized (in shares) 20,000,000 20,000,000    
Preferred stock - shares issued (in shares) 0 0    
Common stock - par value (in dollars per share) $ 0.01 $ 0.01    
Common stock - shares authorized (in shares) 200,000,000 200,000,000    
Common stock - shares issued (in shares) 34,073,670 34,072,909    
Common stock - shares outstanding (in shares) 31,349,317 31,348,556    
Treasury shares (in shares) 2,724,353 2,724,353    
Statements of Operations [Abstract]        
Interest income 586 644 669  
Equity in loss of subsidiaries 14,468 33,448 (8,250)  
Total income (loss) 15,054 34,092 (7,581)  
Compensation (118) (523) (605)  
Professional fees 16 3 57  
Other expense 287 279 440  
Total expense 185 (241) (108)  
Income (loss) before income tax 14,869 34,333 (7,473)  
Income tax benefit 161 (581) 0  
Net income (loss) 14,708 34,914 (7,473)  
Cash flows from operating activities [Abstract]        
Net income (loss) 14,708 34,914 (7,473)  
Adjustments to reconcile net loss to net cash provided by operating activities [Abstract]        
Amortization of unearned ESOP shares 718 306 202  
Stock based compensation 126 145 1,593  
Deferred income taxes (21) (954) (71)  
Equity in (earnings) loss of subsidiaries (14,468) (33,448) 8,250  
Change in other assets and liabilities (1,051) (1,147) (1,537)  
Net cash (used in) provided by operating activities 12 (184) 964  
Cash flows from investing activities [Abstract]        
Capital contributions to subsidiary 0 0 (1,000)  
Net cash used in investing activities 0 0 (1,000)  
Net cash provided by (used in) financing activities 0 0 0  
Net increase (decrease) in cash 12 (184) (36)  
Cash and cash equivalents at beginning of year 337 521 557  
Cash and cash equivalents at end of year $ 349 $ 337 $ 521